In wireless communication systems mobile units or devices are required to operate on batteries and these mobile units will go inactive (or dormant) on the radio frequency (RF) channels after a short period of inactivity of usage for data services, usually 30 to 60 seconds. Therefore, in push-to-talk calls using the wireless data services, both the originating and terminating mobile units must be transitioned to the active state (actually using RF resources) as part of the call setup prior to enabling the push-to-talk function. Once a mobile unit is in the active state, an RF channel has been established and the mobile unit is able to transmit and/or receive data. As known in the art, push-to-talk call applications include transmission of voice and associated signaling data, but advances in packet data networks extend push-to-talk call applications to include images, streaming video, text messaging, stored audio files, and other multi-media.
For typical push-to-talk call applications, the time required for transitioning an originating mobile unit from a dormant state to the active state can be greater than 3 seconds in current implementations. An equal or greater amount of time is required to transition the terminating mobile unit from the dormant to active state, including additional time to actually page the mobile device, as is known in the art. These times do not include transmission time over the air or call processing time required by the dispatch servers. As a result, for the push-to-talk function total delay times experienced by the originating mobile unit may be 10 seconds or greater.
With long call setup times, the advantages of the push-to-talk service as an instant communications method is diminished particularly with call setup times of 8 seconds or even longer which can make the service non-viable in the marketplace. For example, users would prefer to use cellular, rather than holding down the PTT button.
A similar problem exists for group calls in the push-to-talk mode. Call setup times may be even longer since there is a number of terminating mobile units to connect to the originating mobile unit. Although some of the processing time for each of the terminating or target mobile units may overlap, the total call setup time is likely to be even greater than the individual-to-individual call. Therefore, group calls pose an even greater problem for the push-to-talk function in a packet data network.
Accordingly, it would be highly desirable to have a method and system for substantially decreasing the call setup time for private calls and group calls within a push-to-talk packet data network configuration.